This invention relates to printing presses, and in particular, to an apparatus for cleaning a blanket cylinder in an offset printing press without either interrupting the operation of the press or slowing down its operation.
An offset printing press employs a blanket cylinder, that is to say, a rubber cylinder or a rubber-covered cylinder, for the purposes of receiving inked images from a printing plate and of next offsetting the inked images onto paper passed between the blanket cylinders or an impression cylinder. Continuous printing is made possible by wrapping a printing plate or a plurality of printing plates around the surface of a plate cylinder designed for rotation in contact with the blanket cylinder. In operating blanket-to-blanket presses, a web of paper passes between two blanket cylinders mounted such that one blanket cylinder serves as an impression cylinder for the other, resulting in simultaneous printing on both sides of the web of paper. Offset printing, in comparison with the letterpress method of printing, has become the predominant printing method in the newspaper publishing industry due in part to the increased sharpness of the printed images and the ability to print on less even surfaces than are required by the letterpress method, and the lower cost of the printing plates used with offset presses.
However, in continuous offset printing, dust and lint from the web of paper tend to accumulate on the blanket cylinder(s), adversely affecting the quality of the printed product. The accumulation of dust, lint or ink on a blanket cylinder thus presents a serious annoyance and necessitates undesirable down-time for cleaning. The problem is especially acute in the newspaper industry, when, in response to the rising cost of newsprint stock, less expensive grades of paper having higher lint content often are substituted for more expensive grades.
The invention disclosed hereinafter provides an apparatus for cleaning a blanket cylinder during the course of a press run, without interrupting press operation or causing waste during the run. Consequently, a sharper reproduction for a printed product is possible, less down-time is experienced, and grades of paper stock having higher lint contents may be used. The frequency of the automatic engagement and operation of the blanket cleaner of this invention is adjustable by a press operator in response to various anticipated or observed operating parameters such as the length of the press run and the lint content of the paper stock.
The apparatus is suitable for integral construction with an offset press, or for manufacture as an add-on device for retrofitting to an existing press.
One of the objects of this invention is to provide an apparatus for removing dust and lint from a blanket cylinder during the uninterrupted course of a press run.
Another object of this invention is to provide an economical blanket cleaner of simple mechanical action, suitable for retrofitting to existing offset presses.
Another object of this invention is to provide a blanket cleaner adapted for automatic operation at a frequency of engagement adjustable by a press operator.
Another object of this invention is to provide an effective blanket cleaner which will not abrade the blanket cylinder.
Another object of this invention is to provide a blanket cleaner which promote longer blanket life.
Yet another object of this invention is to provide a blanket cleaner which may be operated without causing waste of materials.
Still another object of this invention is to provide a blanket cleaner which operates to provide a longer plate life.
Other objects of this invention will be apparent to those skilled in the art in light of the following description and accompanying drawings.